1. Field of the Invention
This invention relates to a power source which uses the energy accumulated temporarily and stably in a condenser, the accumulated energy being fed from a primary power source such as a solar cell the output of which is unstable.
2. Description of the Prior Art
Conventionally, a condenser C.sub.S and a load 3 are connected in parallel with a power source as shown in FIG. 2. By setting the capacitance of the condenser C.sub.S relatively large, the power source voltage V.sub.L applied to a load and a predetermined operation time after the load 3 stops receiving the electric charge from the power source 1 are stabilized. A reverse current preventive element 2 is connected between the power source 1 and the condenser C.sub.S, if necessary.
The above mentioned power source circuit is disclosed in U.S. Pat. No. 4,434,395 issued Feb. 28, 1984 to Higuchi. It has been disadvantageous that the utilization ratio of the accumulated charges is very low, even if the capacitance of the condenser C.sub.S is increased above the range of the power source voltage V.sub.L effective to operate the load 3 normally, that is, the range from the lowest voltage limit V.sub.OPL to the highest voltage limit V.sub.OPH. The normal operation of the load is not executed in the case that the power source voltage V.sub.L is below the voltage V.sub.OPL. The drawback in utilization is that the accmulated electric charges are not used below the voltage V.sub.OPL. The accumulated electric charges not used as mentioned above are indicated by the oblique lines as shown in FIG. 3. Generally, the condenser has the relation that the capacitance is in inverse proportion to the withstand voltage in the constant cubic volume.